Image files, such as those containing video or film images typically contain a certain amount of noise. In connection with images derived from film, film grain, caused by the random variations in density of the grains, manifests itself as noise. The storage of images containing video and/or film invariably requires a large amount of space, whereas the transmission of such files within a reasonable amount of time requires very high bandwidth. For that reason, image files containing video and/or film usually undergo compression prior to storage and/or transmission. The compression of noise (including film grain) has proven very difficult because of the lack of correlation with the image, whether video or film. For that reason, filtering of the image file prior to compression to remove noise becomes advantageous to achieve a high compression ratio.
Various techniques presently exist for noise filtering. However, such present day techniques often suffer from the disadvantage of being unable to offer fast performance while preserving image detail. Filtering techniques that afford high speed usually do not preserve sufficient image detail, whereas filter techniques that preserve image detail tend to run very slowly.
Thus, a need exists for a technique for filtering noise from an image that achieves both good speed while preserving image details.